Polisher, polishing processing apparatus, polishing processing method, control program to make computer execute polishing, and the record medium

ABSTRACT

At least one polisher is provided that has a rotation axis that is parallel to a normal to a surface of material to be polished, which is mounted on a table. The polisher moves relative to the material to polish and process the surface of the material. The polisher has a structure such that as the polisher polishes the surface of the material an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, is smaller than that at the rotation axis.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Divisional Application of U.S. application Ser. No. 10/754,760 filed Jan. 9, 2004, which is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2003-4434, filed Jan. 10, 2003, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polisher for use in polishing processing apparatuses for polishing the surface of material, a polishing processing apparatus, a polishing processing method, a control program to make a computer execute polishing, and a record medium.

2. Description of the Related Art

There is a method of correcting the shape of the surface of material to be polished. A polisher is placed in parallel to the direction of the normal to the surface of material to be polished. The polisher rotates and moves relative to the material to selectively polish the surface of the material so as to have a desired shape.

In the above method, the distribution of amounts of polishing by the polisher is shaped like a letter W as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-117608. The reason is as follows. When the polisher polishes the material surface with its rotating shaft parallel to the normal to the surface of material, it applies the greatest pressure to that position on the material surface which is located on the extension of the rotating shaft. However, the relative speed between the rotating polisher and the material surface is zero in the position on the extension of the rotating shaft. Though the greatest pressure is applied to the position, the amount of polishing becomes zero and maximized in a position some distance from the extension of the rotating shaft.

Jpn. Pat. Appln. KOKAI Publication No. 2000-117608 therefore discloses a method of selectively polishing convex portions of the surface of material so as to have a desired shape. According to the method, the rotating shaft of a polisher is inclined to the normal of the material surface, and the maximum polishing point of the polisher is made coincident with a group of tops of the convex portions.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, at least one polisher is provided having a rotation axis that is parallel to a normal to a surface of material to be polished, which is mounted on a table. The polisher moves relative to the material to polish and process the surface of the material, and polishes the surface of the material such that an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, is smaller than that at the rotation axis. The present invention is not limited to only a polishing processing apparatus. The present invention can be carried out as a polishing processing method of carrying out a function of the polishing processing apparatus according to an aspect of present invention, a program to execute a method thereof and to control the apparatus, and furthermore, a record medium which memorizes the corresponding program. Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a configuration diagram of a polishing system according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a polishing processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic block diagram of a control apparatus according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating polishing and processing according to the first embodiment of the present invention.

FIGS. 5A to 5C are illustrations of polishing states of material to be polished by a polisher (distribution of polishing amounts).

FIGS. 6A to 6E are illustrations of the basic principle of a polishing method according to the first embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a spindle table unit according to a second embodiment of the present invention.

FIGS. 8A to 8C are schematic configuration diagrams of a polisher according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will now be described with reference to the accompanying drawings.

First Embodiment

FIG. 1 schematically shows a configuration of a polishing system according to a first embodiment of the present invention. The polishing system is chiefly made up of an interferometer 100 that measures the shape of the surface of material 5 to be polished, a computer 101 for the interferometer which controls the interferometer 100 to acquire shape data indicative of the shape of the surface of material 5, a polishing processing apparatus 103 that polishes the surface of material 5, and a computer 102 for the polishing processing apparatus which creates processing data based on the shape data acquired by the interferometer computer 101 and controls the polishing processing apparatus 103.

FIG. 2 schematically shows a configuration of the polishing processing apparatus 103 shown in FIG. 1. The apparatus 103 includes a main body 1. The main body 1 has a base section 1 a and a body section 1 b standing upright on the base section 1 a.

The base section 1 a has a worktable 2. A rotating worktable 3 is placed on the worktable 2. The worktable 2 holds and moves the rotating worktable 3 in the XY direction. The rotating worktable 3 can rotate on the worktable 2 in the direction of arrow D about the z-axis perpendicular to the XY direction. The rotating worktable 3 has a function of controlling the rotation angle thereof and a function of controlling the rotation speed thereof for each rotation angle.

A chuck 4 is provided on the rotating worktable 3 to fix the material 5 to be polished. If the material 5 is shaped like a lens such that its center should be obtained, it is favorable that the rotating worktable 3 and chuck 4 have a centering mechanism. The centering mechanism has a function of conforming the center of rotation of the rotating worktable 3 to a desired center of the material 5. The centering of the centering mechanism can be achieved if the chuck 4 can finely be adjusted in the XY direction on the rotating worktable 3. If the surface of the material 5 is flat and thus its center need not be obtained, a fixed chuck is used for the chuck 4. The chuck 4 is thus replaced according to the shape of material to be polished, the polishing conditions of material, and the like.

A z-axis stage can be provided between the rotating worktable 3 and chuck 4 to allow the material 5 to move in the z-axis direction. The worktable 2 can be designed to mount a plurality of materials to be polished thereon.

The body section 1 b of the main body 1 includes a first up-and-down driving shaft 6 that can move up and down in the direction of double-headed arrow A. A rotating base 7 is mounted on the end of the first up-and-down driving shaft 6 such that it can rotate in the direction of double-headed arrow B. A second up-and-down driving shaft 8 is mounted on the rotating base 7 such that it can move up and down in the direction of double-headed arrow C. A spindle motor 9 is mounted on the end of the second up-and-down driving shaft 8 to fix a spindle 10 to which a polisher 11 is chucked.

FIG. 3 is a schematic block diagram of a control apparatus that controls the polishing processing apparatus described above. Referring to FIG. 3, a control unit 41 has a function of controlling an operation of each unit, and a driving unit 42, a coordinate detecting unit 43, a signal input/output unit 44, a memory 45 and a monitor 46 are connected to the control unit 41. The driving unit 42 drives, for example, the worktable 2, rotating worktable 3, first up-and-down driving shaft 6, rotating base 7, and second up-and-down driving shaft 8 of the polishing processing apparatus shown in FIG. 2. The coordinate detecting unit 43 detects the coordinates of, e.g., the worktable 2 and the nozzle of the polisher 11, or the coordinates of the axis of each of the worktable 2 and polisher 11 which move in the directions of arrows A, B and C. The signal input/output unit 44 controls the spindle 10, a polishing liquid supplying pump (not shown) and the like. The control unit 41 in itself operates to input/output, create, store, select and file control programs, polishing processing conditions and shape data of material 5 to be polished. The results of these operations are displayed on the monitor 46 and stored in the memory 45. The control unit 41 is so configured that it can read data such as programs from a storage medium (not shown). Any storage medium such as a hard disk provided in the control unit 41, an external host computer connected through a communication line, a magnetic disk, and an optical disk can be used as the storage medium for storing programs to be executed by the control unit 41.

The actual polishing processing procedure will now be described with reference to the flowchart shown in FIG. 4.

First, a computer operation for an interferometer is performed as follows. An optical interferometer measures the shape of the surface of material 5 to be polished (step 801). The results of the measurement are displayed on the monitor 46 at the same time when they are input to the control unit 41 and stored in the memory 45 (steps 802 and 803).

Then, a computer operation for a polishing processing apparatus is performed as follows. Data indicative of the measurement results is converted into shape data usable for polishing and processing (step 804). In this step, unnecessary data is deleted and ID and supplementary information are newly added.

In lens polishing and processing, a lens is polished while rotating on its axis. First, the coordinates of the center of the lens are obtained by computation from the shape of the entire surface of the lens (step 805). Then, the shape data is converted from the orthogonal coordinate system to the polar coordinate system (step 806).

The quality of the material 5 is designated and a polishing amount table in desired form is prepared (step 807). Based on the table information and shape data, an amount of polishing of each point of the material is computed (step 808). Confirming a target shape of the material (step 809), processing data including polishing data and polishing time in each point and processing data is created in combination with the quality of the material 5, the type of polishing liquid, the shape of the polisher 11, and the like (step 810) and displayed on the monitor 46 (step 811). The processing data is transferred to the polishing processing apparatus to polish and process the material 5 (step 812).

The basic principle of a polishing method according to the first embodiment will now be described with reference to FIGS. 5A to 5C and 6A to 6E. FIGS. 5A to 5C are illustrations of polishing states (distribution of polishing amounts) of the material 5 to be polished by the polisher 11. For example, the polisher 11 has a configuration that a soft polisher 21 is fixed to a shank 20 made of stainless steel.

FIG. 5A illustrates the distribution of polishing amounts obtained when the rotating polisher 11 is pressed in parallel with the normal to the surface of the material 5 to be polished. The rotation speed of the polisher 11 becomes zero in the vicinity of the center thereof (referred to as “central part” in the present specification) and no polishing action is exerted on the central part. An incomplete polishing portion thus remains in the central part and the section of the surface of the material 5 is shaped like a letter W. FIG. 5B illustrates the distribution of polishing amounts obtained when the polisher 11 moves in the direction perpendicular to the drawing (FIG. 5B). The polisher 11 moves and polishes the incomplete polishing portion in the central part by the neighborhood of the periphery of the polisher 11 (referred to “outer region” in the present application); therefore, the incomplete polishing portion in the central part becomes smaller than that in FIG. 5A. However, the material surface to be polished still has a W-shaped section. If, for example, a lens is polished spirally toward the center from the outer region when its surface has a W-shaped section as shown in FIG. 5B, the central part of the lens is shaped like a letter W as illustrated in FIG. 6A. The shape is thus difficult to correct.

In the first embodiment, the point of the polisher 11 is formed like a cone of, e.g., 100 to increase the pressure applied to the central part of the lens as shown in FIG. 5C. Adopting such a cone-shaped polisher, an incomplete polishing portion can be eliminated from the central part of the lens and thus the section of the surface to be polished can be prevented from being shaped like a letter W. If the lens is polished spirally toward the center from the outer region in this state, the central part of the lens is shaped like a letter V.

The V-shaped portion in the central part of the lens is corrected by varying the polishing force of polishing processing. If polishing time is subtracted at a constant rate as the polisher 11 moves to the center of the lens, the V-shaped portion can be removed as shown in FIG. 6C. The polishing force can be controlled by varying the number of revolutions of the polisher, the amount of pressure of the polisher, the number of times of polishing, or the concentration of the polishing liquid as well as the polishing time.

The amount of polishing in the outer region of the lens is small as shown in FIGS. 6A to 6C. This is because the processing starts from a position in which the outermost region of the lens and the center of the polisher 11 coincide with each other. A uniform amount of polishing can thus be obtained if the processing starts before the polisher 11 is brought into contact with the outermost region of the lens as shown in FIG. 6D.

A very small wave is generated on the entire surface to be polished as seen from FIG. 6D. This wave can considerably be reduced as shown in FIG. 6E by narrowing a movement pitch 29 of the polisher (e.g., 0.05 mm).

Second Embodiment

A second embodiment of the present invention will now be described with reference to FIG. 7. In the second embodiment, the same components as those of the first embodiment are neither described nor illustrated with diagrams. According to the second embodiment, a plurality of polishers 11 can be attached to a spindle unit 104.

The spindle unit 104 shown in FIG. 7 is attached in place of the spindle table 9 including the spindle 10 and polisher 11 shown in FIG. 2. The components not shown in FIG. 7 are the same as those of the first embodiment.

The spindle unit 104 has the following configuration.

A spindle indexing device 12 is attached to the end of a spindle table 9′, and a spindle fixing base 13 is attached to the end of the spindle indexing device 12. A plurality of spindles 10 can be attached to the spindle fixing base 13. A polisher 11 is fixed to each of the spindles 10.

The spindle indexing device 12 can select an arbitrary polisher 11 in accordance with a program command or a manual operation. Polishing can thus be performed with high efficiency and high accuracy.

Third Embodiment

A third embodiment of the present invention will now be described with reference to FIGS. 8A to 8C. In the third embodiment, the same components as those of the first and second embodiments are neither described nor illustrated with drawings. The feature of the third embodiment lies in the point of a polisher.

If the polisher has an acute point as shown in FIG. 5C, the surface of a lens is polished in the shape of the letter V. Since, however, the point of the cone-shaped polisher shown in FIG. 5C has greater pressure than that of the outer region of the polisher, it is easy to wear. In the third embodiment, therefore, a polisher 21 can be shaped to have a spherical point with radius R as shown in FIG. 8A, thus increasing the resistance of the point of the polisher to wearability.

The same advantage as that of FIG. 8A can be obtained by making the angle (α2) of the point of the polisher greater than the angle (α1) of the polisher in itself as shown in FIG. 8B.

The same advantage as that in FIG. 8C can also be obtained by making the hardness of the central part a of the soft polisher 21 the highest and decreasing the hardness toward the outer region 1 of the polisher. The hardness does not decrease gradually toward the outer region of the polisher, but the hardness of only the point of the polisher can be heightened. It is needless to say that the hardness can be varied in stages such as two or three stages.

As described above, the object of the third embodiment is to reduce wear of the point of the polisher. Any configuration will be satisfactory if the object can be attained.

According to the embodiments of the present invention, there is provided a polishing processing apparatus, a polishing processing method, a program to make computers execute polishing, and a record medium capable of polishing and processing with high accuracy by pressing a cone-shaped polisher on the surface to be polished in parallel with the normal of the surface and freely controlling polishing conditions.

Furthermore, the above-described embodiments include various stages of the invention, and various inventions can be extracted by appropriate combinations in a plurality of disclosed constituting elements. For example, even when some constituting elements are removed from all the constituting elements described in the embodiments, the problem described in paragraphs of the problem to be solved by the invention can be solved, and the effect described in the paragraphs of the effect of the present invention is obtained. In this case, a configuration from which the constituting elements are removed can be extracted as the invention.

The following inventions can be extracted from the embodiments described so far: According to the embodiments of the present invention, there is provided a polishing processing apparatus, a polishing processing method, a program to make computers execute polishing, and a record medium capable of polishing and processing with high accuracy by pressing a cone-shaped polisher on the surface to be polished in parallel with the normal of the surface and freely controlling polishing conditions.

According to an aspect of the present invention, at least one polisher is provided having a rotation axis that is parallel to a normal to a surface of material to be polished, which is mounted on a table. The polisher moves relative to the material to polish and process the surface of the material, and polishes the surface of the material such that an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, is smaller than that at the rotation axis. The present invention is not limited to only a polishing processing apparatus. The present invention can be carried out as a polishing processing method of carrying out a function of the polishing processing apparatus according to an aspect of present invention, a program to execute a method thereof and to control the apparatus, and furthermore, a record medium which memorizes the corresponding program.

A polishing processing apparatus according to a second aspect of the present invention is characterized by comprising: a table on which material to be polished is mounted; and at least one polisher according to the first aspect, which has a rotation axis that is parallel to a normal of a surface of the material, the polisher moving relative to the material to polish and process the surface of the material.

A polishing processing method according to a third aspect of the present invention is a polishing processing method which is applied to a polishing processing apparatus including a table on which material to be polished is mounted and at least one polisher having a rotation axis that is parallel to a normal of a surface of the material, the polisher moving relative to the material to polish and process the surface of the material, and is characterized by comprising polishing the surface of the material using the polisher such that an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, becomes smaller than that in the rotation axis.

A control program according to a fourth aspect of the present invention is A control program by which a computer is executed to cause a polishing processing apparatus to polish material to be polished, the polishing processing apparatus including a table on which the material is mounted and at least one polisher having a rotation axis that is parallel to a normal of a surface of the material, the polisher moving relative to the material to polish and process the surface of the material, and the control program is characterized by comprising: displaying shape data of the material before the material is processed; recording and displaying processing conditions set based on the shape data; and polishing the surface of the material using the polisher in accordance with the processing conditions such that an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, becomes smaller than that in the rotation axis.

A recording medium according to a second aspect of the present invention is a recording medium that records a control program by which a computer is executed to cause a polishing processing apparatus to polish material to be polished, the polishing processing apparatus including a table on which the material is mounted and at least one polisher having a rotation axis that is parallel to a normal of a surface of the material, the polisher moving relative to the material to polish and process the surface of the material, and the recording medium is characterized by comprising: displaying shape data of the material before the material is processed; recording and displaying processing conditions set based on the shape data; and polishing the surface of the material using the polisher in accordance with the processing conditions such that an amount of polishing of the material in an outer region of the polisher, which is located away from the rotation axis of the polisher, becomes smaller than that in the rotation axis.

In each of above-mentioned aspects, the following modes are preferable. The following modes may be applied by combining them or applied solely.

(1) The material to be polished is mounted on the table rotatably.

(2) The polishing on the polished surface by the polisher starts before the polisher contacts the outermost portion on the surface to be polished.

(3) The spindle unit which fixes the polisher and moves the desire is further provided and two or more polishers can be installed in the spindle unit.

(4) The polisher is almost shaped like a cone.

(5) The wear of the point of the polisher is smaller than at least that of the outer portion.

(6) In (4) or (5), the polisher has a point which has a spherical shape with radius R or a point whose angle is greater than that of the polisher.

(7) In (4) or (5), hardness of the outer region of the polisher is lower than that of a central part thereof.

According to the embodiment of the present invention, a polishing processing apparatus, a method of processing polishing, a program which makes a computer execute polishing, and a recording medium, which can achieve the polishing with high accuracy can be provided by pushing a conic polisher parallel to the normal on the surface to be polished and controlling the polishing condition freely.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the present invention in its broader aspects is not limited to the specific details, representative devices, and illustrated examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A method of polishing a material, comprising: mounting the material on a rotatable table; polishing the material with a polisher by rotating the polisher about a first rotation axis and rotating the material on the table about a second rotation axis and contacting the rotating polisher to the rotating material, such that, during polishing of the material, a greater amount of the material is polished nearer to the first rotation axis of the polisher at a surface of contact between the polisher and the material than in a region of the surface of contact farther away from the first rotation axis, at an arbitrary position within a range of motion of the polisher with respect to the material to be polished; and changing an angle formed by the first rotation axis and the second rotation axis during the polishing, wherein during the polishing the rotation axis of the polisher is controlled to be parallel to a normal of a surface to be polished of the material.
 2. The method according to claim 1, wherein the polisher is moved with respect to the material during polishing so as to polish the material in a spiral beginning at an outer portion of the material and ending at a central portion of the material.
 3. The method according to claim 1, wherein the polishing of the material is performed first at an outermost region of the material and last at a central region of the material, and the polishing by the polisher is begun before the polisher is brought into contact with an outermost region of the surface to be polished of the material.
 4. The method according to claim 1, further comprising varying a polishing force of the polishing.
 5. The method according to claim 4, wherein the varying of the polishing force is performed by controlling at least one of: a relative moving time between the material and the polisher, a rotation speed of the polisher, an amount of pressure of the polisher, a number of times of polishing, and concentration of a polishing liquid.
 6. The method according to claim 1, wherein the polisher is substantially cone-shaped.
 7. The method according to claim 6, wherein a point of the polisher has a spherical shape.
 8. The method according to claim 6, wherein a point of the polisher has an angle which is greater than an angle between sides of an outer region of the polisher.
 9. The method according to claim 6, wherein a hardness of an outer region of the polisher is lower than a hardness of a point of the polisher.
 10. The method according to claim 6, wherein the polisher has such a structure such that wear of a point thereof is less than wear of at least an outer region thereof.
 11. The method according to claim 10, wherein the point of the polishing member has a spherical shape.
 12. The method according to claim 10, wherein the point of the polishing member has an angle which is greater than an angle between sides of the outer region of the polishing member.
 13. The method according to claim 10, wherein a hardness of the outer region of the polishing member is lower than a hardness of the point thereof.
 14. The method according to claim 1, wherein the material is rotationally symmetric, and an axis of rotational symmetry of the material substantially coincides with the first rotation axis.
 15. The method according to claim 1, wherein a plurality of polishers are mounted on a spindle unit, and the method further comprises selecting a polisher to be used to polish the material from among the polishers mounted on the spindle unit.
 16. The method according to claim 1, wherein the polisher is substantially cone-shaped and has a predetermined apical angle, and wherein during the polishing a side surface of the cone-shaped polishing member is maintained at an angle with respect to the surface to be polished. 